The objective of the third year of this project is to complete the comparison of patterns of gene regulation in spontaneous human tumors and radiation-induced rat tumors with the patterns which have been determined for chemical and viral rat tumors. These results will help to elucidate the mechanism of transformation in spontaneous and radiation-induced tumors -- is a latent virus contributory or not? Comparisons of gene regulation between tumors and normal tissues will be continued on the fraction of members of a gene family which are transcribed, whether both strands of DNA are transcribed within a gene family, and the characterization of double-stranded RNA. This study will also determine the difference in transcription and RNA transport between fetal, newborn, and adult rat liver and kidney and try to correlate the observed changes induced by prenatal carcinogen administration with these patterns and with the RNA pattern of chemically-induced tumors of these organs. All of these studies utilize various techniques of RNA/DNA hybridization.